Apparatus for detecting and maintaining fire in a stoker



| R TEEPLE APPARATUS FOR DETECTING AND MAINTAINING FIRE IN A STOKERFiled June 18, 1955 I I I I I I I u w L. R .TEEPL "lllllmlllll April 18,1939.

Patented Apr. 1 8, 1939 APPARATUS FOR DETECTlNG AND MAIN- TAINING FIREIN A s'roKEa,

Lawrence It. Teeple, Portland, Oreg. Application June 18, 1935, SerialNo. 27,275 6 cams. (01. 236-46) This invention relates generally tocontrols for stokers'and particularly to a method of and apparatus fordetecting and maintaining fire in-a stoker. I M

This invention has a threefold purpose. The

first to shorten the'duration of or to suspend entirely the periodicrefuelingoperation normally initiated by an intermittently operatedswitch-' ing mechanism in order to prevent the refueling 2 operationfrom overheatingthe house when the condition of the fire is good.

The second object is to permit the use of longer periods of refuelingoperation than are feasible with the use of fixed intermittent refuelingset tings in order to make it possible to more adequately rekindle apoor fire without danger of I overheating the house.

The third object is to prevent the'stoker from operating when the tireis completely extinguished or too low to rekindle by finally stoppingthe -stoker if the combustion temperature fails,

to respond prior to the end of a period of time -measured from thebeginning of eachstoker operation. I v

These and other objects are accomplished in the manner set forth in thefollowing specification as illustrated in the accompanying drawing, inwhich:

Fig. 1 is a sectional view through the casing of the device showing awiring diagram and associated controls in a condition when the stack.temperature is down but rising. I I

Fig. 2 is a view similar to Fig. 1 showing the stack temperature up andthe stack, operated switch just. tripped. p l r Fig. 3 is similar toFig. 2 showing a condition 1 in which the fire is out, the stack cold,and the stoker shut down.

Fig. 4 is a section taken Fig. 1.

parts throughout the several views.

Referring in detail to the drawing, there is shown a casing III which isprovided with pillars ll forsupporting same upon a base l2, which issecured to a stack l3 or a combustion chamber in any convenient manner.Baflles I4 are provided on the pillars II to prevent an objectionableamount of heat from passing directly from the stack Hi to the casing l0.i

The base I2 also carries a tubular projection l5 which extends into thestack l3.; The projection I5 is provided with aclosed end It in whichjournals a rock shaft ll whose opposlte alon the line 4.4 i g noverthrow mechanism is well understood and will Similar numbers ofreference refer to similar shaft [1. The purpose of this arrangement isto utilize a change'in the temperatureof the stack I3 t0 produce arotative movementofthe shaft IL ,On'the shaft ,l'l issecured 'a cam 20whose high portion 2| may be rotatably adjusted with relationto theshaftllv by means of a screw 22, which occupies a-curved slot 23 within theindicator plate 24; which is secured to the sha H by means of the screw25.

The screw 22 extends'into the cam 20. The

plate 24 is provided with a .pointer 26, and the 'ment l9 whose opposite'end'is secured to the 'cam 20 is-provided with graduations 21 in orderthatthe proper relationship betweenthe" high portion 2| and the shaft I!may be obtained.

1 Mounted withinthec'asing Hlis a temperature responsive element 28;which is in the form of a strip, o'ne end'of which is secured by meansof the clip 29 to thecasing l0. Near the element 28 is disposed aheating element30, same being preferably mountedon a slidable support 3|for the purpose of adjusting itsrelationship to the element 28, thisrelationship determining the .time required for theelemen-t 30 to movethe element 28 to a tripping position.-

. Mounted on thebase 32 of insulating material is a pivot 33 on which isrockablymounted an arm 34. The arm 34 is provided with a projection 35,on the outer end of which is formed a notch which receives the fulcrum31 of a pair of oppositely disposed contact arms 38 and 39,

which are urged to one extreme position or the other by means of aspring 40. This type of notbe elaborated upon here.

Also mounted within the casing I0 is a block 4| of insulating materialon which is mounted a rocker arm 42 of insulating materiaLsaid arm beingprovided with shoulders 43 and 44. the former of which normally acts asa stop for the element 28 when cool and the latter acts as a stop forthe strip 28 when it is deflected sufficiently by the action of heatfrom the heating element 30.

The arm 42 is urged toward the element 28 by means of a spring 45, whichis secured to the lever 46 which projects from the arm 42. The pivot 41of the arm 42 is fixed to the block 4|, and although the arm 42 is ofinsulating material, the end 48, through which the pivot 41 passes, ispreferably of metal. Attached to the end 48 is a contact arm 49 whichengages a contact post 50 on the block 4| when the element 28 engagesthe face 5| between the shoulders 43 and 44 of the arm 42. When theelement 29 rests upon the shoulder 44, the arm 49 moves away from thepost 50.

A manually operated release button 59 is provided on the casing III, thepurpose of which is to make it possible to reset the arm 42 after itreaches the position shown in Fig. 3. This is brought about by acomplete extinguishment of the fire and is determined by the operationof the stoker for a fixed period of time, after which, if there is notsufiicient heat developed, the stoker will be shut down finally orcompletely until it is manually reset through the operation of thebutton 53.

Associated with the arm 38 is a contact post 60, which is connected toone side of the heating element 30 by means of a wire SI, and associatedwith the arm 39 is a post 62, which is connected by means of a wire 63to a point in the wire 51 between the thermostat 58 and the pressureregulator 59.

A timed interval switching mechanism 64 is interposed in the wire 63,and this may be of any of the well known forms of the device whosefunction it is to periodically close its portion of the motor circuit.The pivot 33 is connected by a wire 55 to a point in the lead 51 whichis between the motor 54 and the thermostat 58. A lead 66 connects oneside of the heating element 30 with the lead 56 of the motor circuit.

It must be understood that the temperature responsive element l9 may beeither of the type which operates its switches at definite temperaturesettings or it may be a friction device tripping the switches on risesand falls of the temperature without regard for the exact value of thetemperature. Also, the timing device may either be an electric heater 30acting on the thermostatic element 28, or it'may be any of the severaltypes of mechanical timing devices such as an electric clock motor.

The heat responsive element I9, which is exposed to stack temperature,serves a dual purpose. First, it shuts oil the timing device, which inthis case is the heater 3!), after the stoker has operated apredetermined length of time and there has been completed an appreciablerise in the stack temperature. But if there has been an insufficientrise in the stack temperature after a period of stoker operationinitiated by any instrument, the motor 54 will be stopped by theseparation of the arm 49 and post 50, which also opens the circuit tothe heater 30.

Due to the fact that the heating element 30 has caused the heatresponsive element 28 to take the position shown in Fig. 3, whichpermits the arm 42 to move under the influence of the spring 45, thestoker motor 54 will now. be finally stopped and cannot be started fromany action arising within the controls themselves but can only bestarted by the manual operation of the button 53, which will reset thearm 42 to the position shown in Figs. 1 and 2.

The second purpose of the element l 9 is accomplished when there is adesired rise in stack temperature before or during a period of stokeroperation as caused by the element 64. This is a switching operationwhich governs the occurrences or length of the stoker refuelingoperation from element 64, which otherwise periodically starts and stopsthe stoker during periods when there are few calls for heat from theelements 58 and 59.

It will be understood that the sole purpose oi the element 94 is tomaintain a lire during periods of inactivity. In other words, as long asthere are few calls for heat from the elements 58 and 59, the element 64serves to periodically operate the stoker a definite number of minutes;but when the stack temperature rises sufficiently to open the refuelinghigh limit switch arm 99, the periodic timing device 54 is preventedfrom starting the stoker, or if it has already started a refuelingoperation, it will be stopped unless further operation is desired by thethermostat 59.

In order to explain the operation of this device, there is shown astoker motor 54, which is connected to a power line 55 by means of alead 56 and a lead 51 which passes through a room thermostat 59 and thenthrough the post 59 and arm 49 to the pivot 41, thence through thepressure regulator 59 to the power line 55.

The operation of the device is as follows:

Assuming that the stoker has.been operated and that this operation hasbeen followed by a period containing no calls for heat from the elements58 and 59, during which time the temper- I ature of the stack'naturallyfalls, the periodic refueling switch 64 now functions, the parts beingin the position shown in Fig. 1 except that the element 55 is holdingopen the circuit of the motor 54-. In this case, the closing of thecircuit throughthe switch 54 permits a flow of current around thethermostat 58 through the arm 99, permitting the motor 54 to operate. Atthesame time, current flows through the arm 99 to the heating element90, causing the element 25 to be deflected at a rate dependent upon thepositioning of the support 9|.

It will be noted that at the commencement of the operation, the element29 rests upon the shoulder 43 of the arm 42. It can be seen that theheating element 30 serves as a timing device,

stoppage of the motor 54, rendering all of the controls inoperativeuntil the device is manually reset by pushing the button 59. If, on theother hand, the temperature does rise within the stack, thereby causingthe element H to rotate the cam 20 to the position shown in Fig. 2, thenthe flow of heat to the element 90 will be interrupted and the element28 will not rise to the shoulder 44, thus preventing the arm 49 frombeing drawn away from the post 50 and the operation of the motor 54stopped.

I claim:

1. An apparatus of the class described consisting ofa heat responsiveelement adapted to be inserted into a smoke stack, a switching mechanismoperated by said heat responsive element, an' intermittently operatedtime controlled switching mechanism adapted to periodically operate astoker, said temperature controlled switching mechanism serving torender the intermittent switching mechanism inoperative when the stacktemperature rises above a predetermined minimum, a second timecontrolled switching mechanism controlled by said heat operatedswitching mechanism, said second time controlled switching mechanismserving to'render the entire controls inoperative whenever the stacktemperature iails to rise to a predetermined minimum within the periodof operation determined by said second mentioned timing device.

2. In a stoker control a stoker motor circuit. a room thermostat forcontrolling said circuit in accordance with room temperaturerequirements, a normally closed thermally controlled switch in saidcircuit, a heater for causing said switch to open after a predeterminedperiod of time, a circuit for energizing said heater, a thermallycontrolled switch in said heater circuit,

said last named switch adapted to open the heater circuit in response toa predetermined heat of combustion of the stoker, whereby in the absenceof heat of combustion the heater causes the stoker circuit switch toopen after a predetermined period of time, and mechanical timing meansfor periodically closing said stoker I circuit and said heater circuitthrough said second named switch during mild weather when the roomthermostat requires an open stoker circuit.

3- In a stoker control, a stoker motor circuit, a normally closedthermally released switch in said motor circuit, a heater which whenenergized is adapted to heat and thereby release said switch after apredetermined period of energization, a room thermostat adaptedsimultaneously to close said motor circuit and to energize said heater,a means responsive to the heat of combustion of the stoker for openingsaid heater circuit to prevent the opening of the normally closed switchwhile the stoker fire is burning normally, and timing means foroperating the motor at intervals in mild weather during periods when theroom thermostat is not in a motor circuit closing position whereby thefire is maintained.

4. In combination a stoker, a stoker control including a stoker circuit,a space thermostat connected to open and close said circuit to operatesaid stoker in accordance with the heat requirements of said space, anormally closed thermally controlled switch in said stoker circuit, aheater for causing said switch to open after a predetermined time lag,means for shunting said space thermostat at fixed intervals of time tooperate the stoker when there is no call for heat and for operating saidheater during said last mentioned motor operations, and a stackthermostat for simultaneously controlling said shunting means and saidheater.

5. In a stoker control, a stoker motor circuit, a room thermostat forcontrolling said circuit in accordance with room temperaturerequirements,

said circuit, a heater for causing said switch to open after apredetermined period of time, a circuit completed by the room thermostatfor energizing said heater, a thermally controlled switch in said heatercircuit, said last named switch adapted to open the heater circuit inresponse to a predetermined heat of combustion of the stokerywhereby inthe absence of heat of combustion the heater causes the stoker circuitswitch to open after a predetermined period of time, and timing meansoperable at intervals during mild weather to close the motor circuit tomaintain the stoker fire and at the same time to close the heatercircuit whereby during periods when the room thermostat is inoperativethe stoker motor is safely operated at intervals as long as a fire ismaintained and is conclusively shut down if insuilicient heat isgenerated to operate said thermally controlled switch.

a normally closed thermally controlled switch in 6. In a stoker havingin combination an electric motor, means comprising a first switch forconnecting the motor to a source of power to operate the stoker inaccordance with heat requirements, means including a second and thirdswitch jointly operable for connecting the motor to the source at timeintervals in the absence of heat requirements, a fourth switch forconclusively interrupting circuits to said first, second and thirdswitches, a timing mechanism for opening the fourth switch apredetermined period after being initiated, means including a fifthswitch for connecting the timing mechanism with second switches so thateither of which upon closing to start the motor also initiates operationof the timing mechanism, whereby upon failure of a rise in stokergenerated temperature within said predetermined period the fourth switchis opened to conclusively shut down the stoker.

LAWRENCE R. 'I'EEPLE.

